Integrins and the proinflammatory phospholipase A2

整合素和促炎磷脂酶 A2

• 批准号: 7142872
• 负责人: YOSHIKAZU TAKADA
• 金额: $ 12.43万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2008-07-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7142872
• 关键词: aging; biological signal transduction; cell differentiation; cell proliferation; cytokine; genetically modified animals; inflammation; integrins; laboratory mouse; monocyte; mutant; nuclear factor kappa beta; phospholipase A2; protein biosynthesis; protein protein interaction; receptor; receptor binding; small interfering RNA; surface plasmon resonance; tissue /cell culture

DESCRIPTION (provided by applicant): The secretory phospholipase A2 group MA (sPLA2-IIA), one of the PLA2 family members, is an acute-phase reactant and its plasma levels are markedly increased during systemic inflammatory conditions by inflammatory cytokines. Further circulating sPLA2-IIA levels constitute an independent risk marker for coronary artery disease and predict cardiovascular events. SPLA2-IIA induces proliferation, differentiation, and cytokine production, and nuclear factor (NF)-kB activation in monocytes, keratinocytes, and endothelial cells. This enzyme hydrolyzes the sn-2 ester bond in the glyceroacyl phospholipids present in lipoproteins and cell membranes, forming nonesterified fatty acids (e.g., arachidonic acid) and lysophospholipids, which act as intracellular second messengers or are further metabolized into potent mediators for inflammation. Indeed, transgenic mice expressing human sPLA2-IIA have hyperproliferation of keratinocytes and more atherosclerosis. However, some biological effects of sPLA2-IIA are independent of its catalytic function, suggesting that they are mediated by sPLA2-IIA binding to specific receptors. A high-affinity receptor for sPLA2-IIA (the M-type receptor) was identified in mice. However, the human sPLA2-IIA does not bind to the human M-type receptor, and the sPLA2-IIA receptor in human was unknown. We recently discovered that human SPLA2-IIA specifically binds to integrin alphaVbetaS. We generated sPLA2 mutants that do not bind to integrins by molecular docking simulation and site-directed mutagenesis. We hypothesize that 1) integrins serve as receptors for sPLA2-IIA, 2) integrins transduce pro-inflammatory intracellular signals from sPLA2- IIA through integrin pathways, and 3) blocking sPLA2-IIA-integrin interaction blocks pro-inflammatory functions of SPLA2-IIA. The integrin-binding defective sPLA2-IIA mutants are powerful tool to study the role of integrins in sPLA2-IIA signaling. To address this hypothesis, we propose to 1) characterize the SPLA2-IIA- integrin interaction and identify integrins that specifically bind to sPLA2-IIA in different cell types (e.g., monocytes). 2) Identify the integrin-mediated SPLA2-IIA intracellular signals using integrin-binding defective sPLA2 mutants in different cell types involved in inflammation. The proposed experiments will determine the roles of integrins in signaling and pro-inflammatory activity of sPLA2-IIA in monocytes and endothelial cells, and will establish integrin-sPLA2-IIA interaction as a novel therapeutic target for inflammatory diseases.

描述(申请人提供)：分泌型磷脂酶A2组MA(sPLA2-IIA)是PLA2家族成员之一，是一种急性时相反应物，在全身炎症状态下，其血浆水平因炎症细胞因子而显著升高。此外，循环sPLA2-IIA水平构成了冠状动脉疾病的独立危险标记，并预测心血管事件。SPLA2-IIA可诱导单核细胞、角质形成细胞和内皮细胞的增殖、分化和细胞因子的产生，以及核因子-kB的激活。这种酶将存在于脂蛋白和细胞膜中的甘油酰磷脂中的sn-2酯键水解，形成非酯化脂肪酸(如花生四烯酸)和溶血磷脂，它们作为细胞内的第二信使或进一步代谢为有效的炎症介质。事实上，表达人sPLA2-IIA的转基因小鼠有角质形成细胞的过度增殖和更多的动脉粥样硬化。然而，sPLA2-IIA的某些生物学效应不依赖于其催化功能，提示它们是通过sPLA2-IIA与特定受体结合而介导的。在小鼠体内发现了sPLA2-IIA(M型受体)的高亲和力受体。然而，人的sPLA2-IIA不与人的M型受体结合，人的sPLA2-IIA受体也是未知的。我们最近发现人sPLA2-IIA与整合素αVbetaS特异性结合。我们通过分子对接模拟和定点突变获得了不与整合素结合的sPLA2突变体。我们假设1)整合素作为sPLA2-IIA的受体，2)整合素通过整合素途径转导sPLA2-IIA的促炎信号，3)阻断sPLA2-IIA-整合素的相互作用阻断sPLA2-IIA的促炎功能。整合素结合缺陷突变体是研究整合素在sPLA2-IIA信号转导中作用的有力工具。为了解决这一假设，我们建议1)表征sPLA2-IIA-整合素的相互作用，并在不同类型的细胞(如单核细胞)中鉴定与sPLA2-IIA特异性结合的整合素。2)利用整合素结合缺陷的sPLA2突变体，在参与炎症的不同细胞类型中鉴定整合素介导的sPLA2-IIA细胞内信号。这些实验将确定整合素在单核细胞和内皮细胞中的信号转导和sPLA2-IIA的促炎活性中的作用，并将建立整合素-sPLA2-IIA相互作用作为炎症性疾病的新治疗靶点。